Scissors bridge and its control device

ABSTRACT

A scissors-type bridge comprising a pair of identical foldable half-spans hingedly interconnected about a common transverse axis, characterized in that it comprises a built-in unfolding mechanism consisting of a pair of triangular members of which two respective vertices are articulated about a common transverse axis, another pair of vertices of said triangular members being articulated on said half-spans respectively, the last pair of vertices being articulated to the ends of a pair of longitudinal traction bars respectively, the other ends of these two longitudinal traction bars being provided with means for coupling them to a control device carried by the launching vehicle and adapted to cause the longitudinal sliding movement of the traction bar to which it is coupled, in one or the other direction, so as to open or close the bridge respectively.

United States Patent 721 Inventors PierreL usvl: 3,305,885 2/1967 Vaillant 1. 14 1 l N gI2ll;:lLCkfCq,b0h0lTarbeS, France PATENTS g2, 1969 844,916 8/1960 GreatBritain 14 1 [4 Paienled J y 1971 Primary Examiner-Jacob L. Nackenoff French Slate, represented by the Minister 0! Armed Forces, Ministerial Delegation for Armaments Technical Direction 01 Land Weapons Manufacturing Workshop of [73] Assignee Tarbes, Paris, France [32] Priority Mar. 1, 1968 [33] France [31] 141,908

[54] SCISSORS BRIDGE AND ITS CONTROL DEVICE Attorneys-Robert E. Burns and Emmanuel .l. Lobato ABSTRACT! A scissors-type bridge comprising a pair of identical foldable half-spans hingedly interconnected about a common transverse axis, characterized in that it comprises a built-in unfolding mechanism consisting of a pair of triangular members of which two respective vertices are articulated about a common transverse axis, another pair of vertices of said triangular members being articulated on said half-spans respectively, the last pair of vertices being articulated to the ends of a pair of longitudinal traction bars respectively, the other ends of these two longitudinal traction bars being provided with means for coupling them to a control device carried by the launching vehicle and adapted to cause the longitudinal sliding movement of the traction bar to which it is coupled, in one or the other direction, so as to open or close the bridge respectively.

PATENTED JUL27 um sum 1 or 3 :rfmn:FLPHHW,HLMHUWW SCISSORS BRIDGE AND ITS CONTROL DEVICE BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION It is the object of the present invention to avoid this inconvenience by providing a scissors-type bridge comprising a mechanism whereby the unfolding operation can be accomplished by exerting a direct tractive effort by means of a hydromechanical control device located at any end of the bridge and carried by the launching vehicle.

To this end, the scissors-type bridge according to the present invention, which comprises a pair of identical foldable half-spans hingedly interconnected about a common transverse axis, is characterized in that it comprises a built-in un' folding mechanism consisting of a pair of triangular members of which two respective vertices are articulated about a common transverse axis, another pair of vertices of said triangular members being articulated on said half-spans respectively, the last pair of vertices being articulated to the ends of a pair of longitudinal traction bars respectively, the other ends of these two longitudinal traction bars being provided with means for coupling them to a control device carried by the launching vehicle and adapted to cause the longitudinal sliding movement of the traction bar to which it is coupled, in one or the other direction, so as to open or close the bridge respectively.

According to a complementary feature characterizing this invention, the bridge opening and closing control device consists of a double-acting hydraulic actuator of which the piston rod carries at its inner end a rotary head adapted to be coupled by means of a bayonctjoint to one of a pair of compensators secured to the ends of the longitudinal traction bars of the bridge.

The bridge according to this invention is advantageous in that its unfolding mechanism is so designed that the use of chains, ropes and pulleys can be dispensed with, thus eliminating frequent checkings and a particular maintenance. The simplified design of this mechanism affords a substantial reduction in weight, so that the useful width of the bridge may he increased up to about 4 meters 160 inches), including the side strips adapted to be mounted on both half-spans.

Since all the component elements of the unfolding mechanism are simple and easy to manufacture, the final cost of the bridge according to this invention is reduced to a substantial degree, comparing with hitherto known bridges of the same type.

Besides, the bridge unfolding control device is more l'lexi ble, easier to operate and requires less maintenance. This maintenance consists simply in lubricating the articulations, the compensators rails and the bearing or guide rollers of the longitudinal traction bars.

BRIEF DESCRIPTION OF THE DRAWINGS A typical form of embodiment of the bridge and its control device constituting the subject matter of this invention will now be described by way of example with reference to the attached drawings, in which:

FIG. 1 is a longitudinal section showing a bridge constructed according to the teachings of this invention, the two half-spans being shown in their horizontal position;

FIG. 2 is a plan view from above of the structure shown in FIG. 1;

FIG. 3 is a diagrammatic longitudinal section showing on a larger scale the bridge unfolding mechanism as it appears when the half-spans are unfolded to their horizontal position;

FIG. 4 is a longitudinal section showing the unfolding mechanism when the two half-spans of the bridge are folded against each other;

FIG. 5 is an axial section showing the structure of the hydraulic actuator controlling the movements of the bridge half-spans;

FIG. 6 is a cross-sectional view taken along the line VIVI of FIG. 5', i v

FIG.'7 is a cross-sectional'view taken along the line VILVII of FIG. 5;

FIG. 8 is a cross-sectional view taken along the line VIII-VIII of FIG. I;

FIG. 9 is a cross-sectional view corresponding to FIG. 8, but showing the hydraulic actuator disengaged from the bridge half-span.

DESCRIPTION OF THE PREFERRED EMBODIMENT The bridge according to this invention comprises two halfspans 1 and 2 articulated to each other about a transverse axis, for example a shaft 3. These half-spans I, 2 are adapted to be folded against each other for transporting the bridge to the place where it is to be used. Both half-spans l and 2 are identical and consist each of a pair of longitudinal box section members 4 and 5 assembled and braced by planks. Both half-spans are constructed from high-tensile strength light-alloy sections and their component elements are assembled by welding and riveting. The longitudinal box section members 4 and 5 are provided at their ends with bank-engaging steel beaks 6. The track or treadway width available with the pair of box section members 4 and 5 may be increased by means of detachable widening elements. The planking elements comprise hooking means. The space available between the box section members 4 and 5 is adapted to house the traction-operated unfolding mechanism and the gripping cross members.

The bridge unfolding mechanism will now be described in detail with reference more particularly to FIGS. 3 and 4 of the drawings, in which it is clearly apparent that this mechanism comprises a pair of triangular units consisting each of bars rigidly assembled by their ends and disposed symmetrically in relation to a transverse plane x-y containing the axis of the pivot shaft 3 of the two half-spans. Two triangles 7 constituting the first pair are disposed symmetrically in relation to the longitudinal centerline of the bridge, like the other triangles 8 constituting the other pair. These triangles 7 and 8 may be either isosceles triangles as shown in the drawing, or of another type. The pair of vertices 7a-and the pair of vertices 8a of the pair of triangles 7 and of the pair of triangles 8, which are formed by the intersection of two equal sides, are pivoted to a common transverse shaft 9. Other vertices 7b of triangles 7 are pivotedto the lower portion of half-span 2 about a shaft II, and similarly the other vertices 8b of triangles 8 are pivoted to the lower portion of the other half-span I, about a transverse shaft 12.

The last pair of vertices 7c of both triangles 7 are interconnected by a transverse shaft 13 having anchored thereto 3. Iongitudinal traction bar 14 and similarly the last vertices 8c of both triangles 8 are interconnected by a transverse shaft 15 to which another longitudinal traction bar 16 is anchored.

Both traction bars 14 and 16 have suitable diameter and length, and comprise at their end adequate members for coupling these bars to the shafts l3 and 15, on the one hand, and to compensators l7 and 18 on the other hand. As shown in the cross-sectional view of FIG. 8, compensator 17 is guided by longitudinal guide rails 19 rigid with the box section members 4 and 5, respectively, so that they can slide in the longitudinal direction.

The bridge operation is controlled by means of a doubleacting hydraulic actuator of the cylinder and piston type 21 carried by the launching vehicle 22 shown only diagrammatically and partially in FIG. 1. Due to the symmetrical arrangement of the bridge structuretaccording to this invention, the actuator 21 may be coupled to one or the other of said compensators l7 and 18.

As better illustrated in FIG. 5, the hydraulic double-acting actuator 21 of conventional design comprises a cylinder or body 23 of which the frustoconical end portion 24 fits in a cor respondingly shaped cavity 25 provided in a crossmember 26 of half-span 1. Besides, the piston 27 of this actuator is rigid with a hollow rod 28 of which the outer end has a rotary head 29 mounted thereon. This rotary head 29 is operatively coupled to the compensator 17 by means ofa bayonet joint. As illustrated in FIG. 6, the compensator 17 has formed therethrough a circular hole 3| having two lateral extensions in the form of a pair of symmetrical notches 32 and 33. The aforesaid rotary head 29 of the actuator piston-rod has a substantially cylindrical configuration and lateral extensions in the form of shoulders 34 and 35 having the same shape as, but slightly smaller dimensions than, the aforesaid notches 32 and 33. Furthermore, this rotary head 29 is rigidly assembled by means of a cross pin 36 with a spindle 37 extending coaxially through the hollow rod 28 of the piston; this spindle 37 is rotatably solid with a shaft rigid with a spur pinion 38. This spur pinion 38 is in constant meshing engagement with a pair of transverse toothed racks 39 and 41 formedon the'lateral surfaces of a pair of small-piston rods 42 and 43 of a pair of small-sized double-acting transverse actuators 44 and 45, respectively.

The dimensions of pinion 38 and racks 39, 41 are such that the normal stroke of the rods of pistons 42 and 43 corresponds to a 90 rotation of pinion 38 and therefore of rotary head 29. Therefore, when this rotary head has been engaged through the compensator 17 by causing its shoulders 34 and 35 to pass through the corresponding notches 32 and 33, it is only necessary to supply hydraulic fluid under pressure to the small actuators 44 and 55 for pivoting said head through 90 and lock same in said compensator 17. Of course, the head is released by operating same in the opposite direction.

The operation of the above-described assembly may be summarized as follows: Assuming the head 29 of actuator 21 to be locked in a cavity provided to this end in compensator 17, the fluid under pressure controlled from within the launching vehicle 22 is fed to the actuator cylinder 23. The fluid pressure causes the piston 28 to recede into this cylinder 23. Thus, the compensator 17 is moved in the axial direction (i.e. to the right as seen in FIG. 5) and carries along the traction bar 14 coupled thereto which, by acting upon the relevant pair of triangles 7, 8 actuates the free half-span 2 so as to unfold same. During this movement these triangles 7 and 8 act both as control levers for operating the pair of articulated halfspans, and as force multiplicators.

When it is desired to recover the scissors-type bridge according to this invention, the reverse sequence of operations is performed; starting from the disengagement condition shown in FIG. 9, the rotary head 29 of the main actuator is first to be engaged into compensator l7, and to be locked therein by rotating same through under-the control of said small actuators and rack assembly.

Of course, the specific form of embodiment of the invention which is described hereinabove with reference to the accompanying drawing should not be construed as limiting the scope of the invention, since many modifications may be brought thereto without departing from the basic principles of the invention as set forth in the appended claims.

What we claim is:

l. A scissorstype bridge actuated from a launching vehicle carrying a control device, comprising a transverse pivot axis, two identical foldable half-spans hingedly interconnected about said transverse pivot axis, a pair of triangular members, each having a first vertex ivoted to the respective half-span in laterally spaced relations ip to the transverse pivot axis, said triangular members being oppositely directed and having second corresponding vertices pivotally interconnected-in vertically spaced relationship above said transverse pivot axis when said half-spans are in alignment, each of said triangular members having a leg extending from the second corresponding vertex outwardly towards the outer end of the respective half-span and terminating in the corresponding third vertex of the triangular member, traction bars pivotally connected to the respective third vertices of the triangular members, and extending therefrom towards the end of the respective halfspan, and coupling members onthe end of each bar, adapted to be engaged by the control device of the launching vehicle, whereby one of said bar is longitudinally moved to and from by said control device for opening and closing the bridge, respectively.

2. The scissors-type bridge of claim 1, wherein each triangular member consists of a pair of triangles comprising bars rigidly assembled to each other and disposed symmetrically in relation to the longitudinal plane of symmetry of the bridge.

3. Scissors-type bridge according to claim 2, comprising a second transverse shaft mounted on each traction bar, the second pair of vertices of each pair of triangles being articulated to the corresponding bar by means of said second transverse shaft, respectively.

4. Scissors-type bridge according to claim 1, comprising, at the outer end of each half-span, longitudinal guide rails, a compensator. secured to the relevant end of the traction bar and adapted to slide in said longitudinal guide rails, a crossmember and a recess formed in said crossmember, said control device carried by the launching device comprising a double-acting hydraulic actuator, the end of which is engaged in the recess of said crossmember.

5. Scissors-type bridge according to claim 4, wherein said hydraulic actuator comprises a piston, a rod secured to said piston, a rotary head mounted at the outer end of said rod and a bayonet mounting for coupling said rotary head to one of said compensators secured to said traction bars.

6. Scissors-type bridge according to claim 5, wherein said hydraulic actuator comprises a pinion coupled to said rotary head, a smaller transverse double-actinghydraulic actuator, and a rack rigid with the rod of said transverse actuator, said pinion being in constant meshing engagement with said rack. 

1. A scissors-type bridge actuated from a launching vehicle carrying a control device, comprising a transverse pivot axis, two identical foldable half-spans hingedly interconnected about said transverse pivot axis, a pair of triangular members, each having a first vertex pivoted to the respective half-span in laterally spaced relationship to the transverse pivot axis, said triangular members being oppositely directed and having second corresponding vertices pivotally interconnected in vertically spaced relationship above said transverse pivot axis when said half-spans are in alignment, each of said triangular members having a leg extending from the second corresponding vertex outwardly towards the outer end of the respective half-span and terminating in the corresponding third vertex of the triangular member, traction bars pivotally connected to the respective third vertices of the triangular members, and extending therefrom towards the end of the respective half-span, and coupling members on the end of each bar, adapted to be engaged by the control device of the launching vehicle, whereby one of said bar is longitudinally moved to and from by said control device for opening and closing the bridge, respectively.
 2. The scissors-type bridge of claim 1, wherein each triangular member consists of a pair of triangles comprising bars rigidly assembled to each other and disposed symmetrically in relation to the longitudinal plane of symmetry of the bridge.
 3. Scissors-type bridge according to claim 2, comprising a second transverse shaft mounted on each traction bar, the second pair of vertices of each pair of triangles being articulated to the corresponding bar by means of said second transverse shaft, respectively.
 4. Scissors-type bridge according to claim 1, comprising, at the outer end of each half-span, longitudinal guide rails, a compensator secured to the relevant end of the traction bar and adapted to slide in said longitudinal guide rails, a crossmember and a recess formed in said crossmember, said control device carried by the launching device comprising a double-acting hydraulic actuator, the end of which is engaged in the recess of said crossmember.
 5. Scissors-type bridge according to claim 4, wherein said hydraulic actuator comprises a piston, a rod secured to said piston, a rotary head mounted at the outer end of said rod and a bayonet mounting for coupling said rotary head to one of said compensators secured to said traction bars.
 6. Scissors-type bridge according to claim 5, wherein said hydraulic actuator comprises a pinion coupled to said rotary head, a smaller transverse double-acting hydraulic actuator, and a rack rigid with the rod of said transverse actuator, said pinion being in constant meshing engagement with said rack. 